Extreme Magnetoconvection

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Thermal convection, i.e., a fluid flow in which hot fluid raises against gravity, is ubiquitous in nature and technology. Sometimes, the fluid is electrically conducting and moves in the presence of a magnetic field. For example, this happens in the outer core of the Earth, in processing of steel and aluminum, or growth of semiconductor crystals for electronics. Most closely related to the project are the examples from the two emerging energy technologies: nuclear fusion and energy storage in liquid metal batteries. The interaction with the magnetic field entirely changes the thermal convection. Unexpected patterns appear in the flow, such as strong internal jets, fluctuations of temperature with very high amplitude, spots of anomalously high or low temperature, and so on. The ability of the fluid to transport heat also changes dramatically. The project considers these effects in the case when both the convection and the magnetic field are very strong. Computer simulations are performed in cooperation with experiments conducted by project partners in the USA and Europe. The goals of the project are to understand the change of convection flow and to determine consequences for technology and nature. Thermal convection in an electrically conducting fluid (e.g., a liquid metal) in the presence of a magnetic field is analyzed computationally. The case of very large Grashof and Hartmann numbers is considered. It has been found recently that, as conventional turbulence is suppressed by the magnetic field, such flows acquire counter-intuitive extreme features, such as high-amplitude temperature fluctuations, anomalously strong convective heat transfer carried by quasi-two-dimensional jets, etc. The project applies high-resolution simulation approach in cooperation with experiments by research partners to understand the mechanisms of the flow modification and analyze the implications for emerging energy technologies, materials processing, and astro- and geophysical systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.